This project will produce highly advantageous methods for the analysis of selected neurotransmitters, their precursors, their metabolites, and their related metabolic enzymes. Instead of employing the already established detection/quantitation techniques of radiochemistry, gas chromatography - mass fragmentography, or fluorescence, we will measure the catecholamines and indoleamines by liquid chromatography with electrochemical detectors. This methodology affords unsurpassed sensitivity, substantial selectivity, reasonable time requirements, true simultaneous determination of a number of components, and requires no derivatization or sample splitting prior to analysis. We will apply this methodology to the development of specific procedures for norepinephrine, dopamine, serotonin, 3-methoxytramine, noremetanephrine, L-DOPA, 5-hydroxytryptophan, melatonin, 5-methoxytryptamine, and 5-hydroxyindole-3-acetic acid. Additionally, through analysis of appropriate products we will produce enzymatic assay procedures (mostly in vitro) for tyrosine hydroxylase, DOPA decarboxylase, dopamine-beta-hydroxylase, catechol-D-methyltransferase, monoamine oxidase, and tryptophan hydroxylase. General extension of the liquid chromatography/electrochemical detection technique will be attempted in the areas of increasing sensitivity through electrical isolation of the system, decreasing time requirements by automation, and increasing selectivity through better chromatographic resolution.